Association of Serum Potassium with Arrhythmias and Cardiovascular Mortality: A Systematic Review and Meta-Analysis of Observational Studies

Aim:

To provide the first systematic review and meta-analysis of observational studies on the association of abnormal serum potassium (K⁺) and cardiovascular (CV) outcomes.

Methods:

Studies were searched for in Medline and Web of Science. Inclusion of a study required an observational design, serum K⁺ measurements, and investigation of arrhythmias or cardiovascular mortality (CVM). Data synthesis was performed using random effects model meta-analyses.

Results:

Among 41 included studies, 19 were pooled in meta-analyses (risk ratio [95% confidence interval]). In the older general population, low serum K⁺ was associated with a 1.6-fold and a 1.8-fold increased risk of supraventricular (1.62 [1.02 – 2.55]) and ventricular (1.76 [1.43 – 2.09]) arrhythmias, respectively. In contrast, high serum K⁺ was associated with increased CVM (1.35 [1.10 – 1.66]). In patients with acute myocardial infarction (AMI), the risk of ventricular arrhythmias was increased for both low (4.09 [1.57 – 10.66]) and high (2.65 [1.70 – 4.13]) serum K⁺. The same U-shaped association was observed in diuretic-treated hypertensive patients and a composite CV outcome (2.6-fold increased risk with hypokalemia and 1.7-fold increased risk with hyperkalemia). In heart failure patients, only hypokalemia was associated with increased CVM (1.27 [1.06 – 1.52]). In patients with chronic kidney disease (CKD) and patients on dialysis, only hyperkalemia was associated with a 1.9-fold increased risk of a composite CV outcome (1.87 [1.66 – 2.10]) and a 1.8-fold increased CVM (1.81 [1.18 – 2.76]), respectively.

Conclusion:

Abnormal serum K⁺ was associated with CV outcomes in the older general population and other high-risk populations, such as patients with hypertension, AMI, heart failure, CKD, or dialysis. Randomized controlled trials are needed to determine which populations may profit from more frequent monitoring and subsequent interventions against hypo- or hyperkalemia, such as withdrawal of medications that affect serum K⁺.